Resin composition for molding

ABSTRACT

The present invention provides a resin composition for molding that can provide a molded body having excellent thermal stability, high impact resistance, and high surface smoothness. The present invention also provides a molded body including the resin composition for molding. Provided is a resin composition for molding including: a chlorinated polyvinyl chloride; an acrylic processing aid; and an impact resistance modifier, the acrylic processing aid containing an acrylic resin having a weight average molecular weight of 500,000 to 5,000,000, the resin composition containing the acrylic processing aid in an amount of 0.2 to 10 parts by mass and the impact resistance modifier in an amount of 0.5 to 8.0 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride.

TECHNICAL FIELD

The present invention relates to a resin composition for molding that can provide a molded body having excellent thermal stability, high impact resistance, and high surface smoothness. The present invention also relates to a molded body including the resin composition for molding.

BACKGROUND ART

Polyvinyl chlorides (hereinafter referred to as PVCs) are materials excellent in mechanical strength, weather resistance, and chemical resistance, and have been used in various fields. PVCs, however, have poor heat resistance. This has led to the development of chlorinated polyvinyl chlorides (hereinafter referred to as CPVCs), which are PVCs chlorinated to have improved heat resistance. While PVCs cannot be used with hot water because they have low heat deformation temperature and a maximum usable temperature of around 60° C. to 70° C., CPVCs can be used with hot water because they have a heat deformation temperature higher than that of PCVs by as much as 20° C. to 40° C. For example, CPVCs are suitably used in heat-resistant pipes, heat-resistant joints, heat-resistant valves, heat-resistant plates, and the like.

CPVCs have higher viscosity than typical PVCs and thus have long stress relaxation time. Molded products of CPVCs, such as pipes, thus have poor smoothness on the surface (inner surface). In a pipe having poor smoothness on the inner surface, stagnation is more likely to occur due to the influence of the irregularity, which easily causes bacteria growth and dust accumulation. Pipes of CPVCs are thus difficult to use as pipes for ultrapure water for plants or lined pipes.

To overcome the situation, CPVCs may be mixed with metal compounds, stabilizers, or the like to have increased thermal stability, and may be molded at an increased molding temperature or molded with an extended residence time in the die so as to impart surface smoothness.

For example, Patent Literature 1 discloses a CPVC containing an organotin stabilizer, an oxidized polyethylene wax, an improver, a lubricant, a processing aid, a pigment, and the like at a specific ratio.

The technique of Patent Literature 1, however, provides insufficient thermal stability. Thermal stabilizers thus have been added in large amounts, but it impairs the natural heat resistance of CPVCs. Furthermore, to maintain the thermal stability, processing aids having a low molecular weight have been used. However, a molded body having satisfactory smoothness at the inner surface has yet to be achieved.

Patent Literature 2 discloses a method for producing a molded body having excellent heat resistance and excellent smoothness, which includes molding of a CPVC having a chlorine content, a porosity, and a volume of 0.001 to 0.1 μm pores in predetermined ranges.

This method disadvantageously involves a complicate step for producing a raw material resin.

CITATION LIST Patent Literature

-   Patent Literature 1: JP H09-316267 A -   Patent Literature 2: JP 2001-278992 A

SUMMARY OF INVENTION Technical Problem

The present invention aims to provide a resin composition for molding that can provide a molded body having excellent thermal stability, high impact resistance, and high surface smoothness. The present invention also aims to provide a molded body including the resin composition for molding.

Solution to Problem

The present invention relates to a resin composition for molding including: a chlorinated polyvinyl chloride; an acrylic processing aid; and an impact resistance modifier, the acrylic processing aid containing an acrylic resin having a weight average molecular weight of 500,000 to 5,000,000, the resin composition containing the acrylic processing aid in an amount of 0.2 to 10 parts by mass and the impact resistance modifier in an amount of 0.5 to 8.0 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride.

The present invention is described in detail below.

The inventors made intensive studies to find out that a molded body having excellent thermal stability, high impact resistance, and high surface smoothness can be produced by adding predetermined amounts of an acrylic processing aid containing an acrylic resin having a specific weight average molecular weight and an impact resistance modifier to a resin composition for molding containing a chlorinated polyvinyl chloride. The inventors thus completed the present invention.

In particular, in the present invention, not only the surface roughness of the resulting molded body but also the filtered waviness thereof can be reduced. In tubular components, the filtered waviness on the inside is deeply related to fluidity. The molded body including the resin composition for molding of the present invention can have reduced filtered waviness, and as a result, can have a uniform thickness with less thickness variation. The molded body thus can improve the internal pressure creep performance for a long time.

The resin composition for molding of the present invention contains a chlorinated polyvinyl chloride (hereinafter also referred to as a “CPVC”).

Preferably, the CPVC has structural units (a) to (c) represented by the following formulae (a) to (c), and the proportion of the structural unit (a) is 17.5 mol % or less, the proportion of the structural unit (b) is 46.0 mol % or more, and the proportion of the structural unit (c) is 37.0 mol % or less, relative to the total number of moles of the structural units (a), (b), and (c). Such a CPVC has high thermal stability and satisfactory molding processability. [Chem. 1] —CCl₂—  (a) —CHCl—  (b) —CH₂—  (c)

The molar ratios of the structural units (a), (b), and (c) in the CPVC reflect the site to which chlorine is introduced at the time of chlorination of the polyvinyl chloride (PVC). Ideally, the PVC prior to chlorination is substantially in a state where the proportion of the structural unit (a) is 0 mol %, the proportion of the structural unit (b) is 50.0 mol %, and the proportion of the structural unit (C) is 50.0 mol %. As chlorination proceeds, however, the proportion of the structural unit (c) decreases, while the proportions of the structural unit (b) and the structural unit (a) increase. At this time, nonuniformity of the chlorinated state will increase in a case where the proportion of the structural unit (a), which is unstable with a large steric hindrance, excessively increases, or in a case where the chlorinated site and the unchlorinated site are unevenly present within the same particle of the CPVC. When this nonuniformity increases, the thermal stability of the CPVC will be greatly impaired.

On the other hand, in the present invention, the molar ratios of the structural units (a), (b), and (c) in the CPVC are set within the above range, so that the CPVC has improved uniformity and satisfactory thermal stability.

In the present invention, the proportion of the structural unit (a) relative to the total number of moles of structural units (a), (b), and (c) is 17.5 mol % or less, preferably 16.0 mol % or less, and preferably 2.0 mol % or more.

The proportion of the structural unit (b) relative to the total number of moles of structural units (a), (b), and (c) is 46.0 mol % or more, preferably 53.5 mol % or more, and preferably 70.0 mol % or less.

The proportion of the structural unit (c) relative to the total number of moles of structural units (a), (b), and (c) is 37.0 mol % or less, preferably 30.5 mol % or less, and preferably 1.0 mol % or more.

In the present invention, it is particularly preferred that the proportion of the structural unit (b) be 58.0 mol % or more, and the proportion of the structural unit (c) be 35.8 mol % or less. With this structure, higher thermal stability can be achieved.

The molar ratios of the structural units (a), (b), and (c) in the CPVC can be measured by molecular structure analysis using NMR. NMR analysis can be performed in accordance with the method described in R. A. Komoroski, R. G. Parker, J. P. Shocker, Macromolecules, 1985, 18, 1257-1265.

A PVC portion not chlorinated in the molecular structure of the CPVC can be represented by a structural unit (d) shown in the following formula (d). This portion is herein referred to as a “VC unit”.

In the CPVC used in the present invention, the amount of a sequence of four or more VC units in the molecular structure is preferably 30.0 mol % or less. As used herein, the “sequence of four or more VC units” means a portion consisting of four or more VC units joined in series. [Chem. 2] —CH₂—CHCl—  (d)

A VC unit present in the CPVC is a starting point of dehydrochlorination, and the presence of continuous VC units tends to cause a continuous dehydrochlorination reaction called the “zipper reaction”. That is, the greater is the number of a sequence of four or more VC units, the more readily dehydrochlorination will occur, which reduces thermal stability in the CPVC. Therefore, the proportion of a sequence of four or more VC units is preferably 30.0 mol % or less, more preferably 28.0 mol % or less. When the chlorine content of the CPVC is 69% by mass or more and less than 72% by mass, the proportion of a sequence of four or more VC units is preferably 18.0 mol % or less, more preferably 16.0 mol % or less.

The amount of a sequence of four or more vinyl chloride units in the molecular structure described above can be measured by molecular structure analysis using NMR described above.

The CPVC preferably has a chlorine content of 63 to 72% by mass.

A chlorine content of 63% by mass or more leads to sufficient heat resistance of the molded product. A chlorine content of 72% by mass or less leads to improved moldability.

The chlorine content is more preferably 66% by mass or more, and more preferably 69% by mass or less.

The chlorine content of the CPVC can be measured in accordance with the method described in JIS K 7229.

The CPVC preferably has a gelling time of 100 to 200 seconds, more preferably 110 to 190 seconds.

When the gelling time is within the range, the collapse and fusion of the resin appropriately proceeds, so that the appearance and the physical properties can be enhanced in molding.

The gelling time means the time at which the motor torque reaches its maximum when a sample prepared by adding a thermal stabilizer, a lubricant, and an impact resistance modifier to the CPVC is put in Labo PlastoMill or the like and the rotor is rotated.

The CPVC preferably has a UV absorbance at a wavelength of 216 nm of 8.0 or less, more preferably 0.8 or less.

In an ultraviolet absorption spectrum, a wavelength of 216 nm is the wavelength at which —CH═CH—C(═O)— and —CH═CH—CH═CH—, which are heterogeneous structures in the CPVC, show absorption.

From the value of the UV absorbance of the CPVC, the heterogeneous structures in the molecular chain during the chlorination reaction can be quantified and thus used as an index of thermal stability. In the molecular structure of the CPVC, a chlorine atom attached to carbon adjacent to double-bonded carbon is unstable. Thus, dehydrochlorination occurs from this chlorine atom as the starting point. That is, the greater is the value of UV absorbance at the wavelength of 216 nm, the more readily dehydrochlorination will occur, which results in reduced thermal stability.

In particular, when the chlorine content of the CPVC is 63% by mass or more and less than 69% by mass, the value of the UV absorbance is preferably 0.8 or less. When the value of the UV absorbance exceeds 0.8, the influence of the heterogeneous structures in the molecular chain will be significant, which may result in low thermal stability.

When the chlorine content of the CPVC is 69% by mass or more and 72% by mass or less, the value of the UV absorbance is preferably 8.0 or less. When the value of the UV absorbance exceeds 8.0, the influence of the heterogeneous structures in the molecular chain will be significant, leading to low thermal stability.

In the CPVC, time required for the amount of dehydrochlorination at 190° C. to reach 7,000 ppm is preferably 60 seconds or longer, more preferably 100 seconds or longer.

The CPVC undergoes pyrolysis at high temperatures, and produces HCl gas during pyrolysis. Generally, as the degree of chlorination of the CPVC increases, the number of VC units decreases, and thus, the amount of dehydrochlorination tends to decrease. As the degree of chlorination increases, however, a nonuniform chlorinated state or the amount of the heterogeneous structures increases, which reduces thermal stability. Thus, an increase in the nonuniform chlorinated state or the amount of the heterogeneous structures can be analyzed by measuring the amount of dehydrochlorination. For example, the time required for the amount of dehydrochlorination at 190° C. to reach 7,000 ppm can be used as an index of thermal stability. The shorter is the time, the lower will be the thermal stability.

In particular, when the chlorine content of the CPVC is 63% by mass or more and less than 69% by mass, the time required for the amount of dehydrochlorination at 190° C. to reach 7,000 ppm is preferably 60 seconds or longer. When the time is shorter than 60 seconds, thermal stability will be greatly impaired. Thus, the time is preferably 60 seconds or longer, more preferably 70 seconds or longer, still more preferably 80 seconds or longer.

When the chlorine content of the CPVC is 69% by mass or more and 72% by mass or less, the time is preferably 100 seconds or longer. When the time is shorter than 100 seconds, thermal stability will be significantly low. The time is therefore preferably 100 seconds or longer, more preferably 120 seconds or longer, still more preferably 140 seconds or longer.

The time required for the amount of dehydrochlorination at 190° C. to reach 7,000 ppm can be measured as follows. Initially, 1 g of the chlorinated polyvinyl chloride is placed in a test tube and heated at 190° C. in an oil bath. The produced HCl gas is then collected. The collected HCl gas is dissolved in 100 mL of ion-exchange water, and the pH is measured. The HCl concentration (ppm) (that is, the number of grams of HCl produced per million grams of the chlorinated polyvinyl chloride) is calculated based on the pH value. The time required for the HCl concentration to reach 7,000 ppm is then measured.

The CPVC is a resin obtained by the chlorination of a polyvinyl chloride (PVC).

As the PVC, a vinyl chloride homopolymer, a copolymer of a vinyl chloride monomer and a monomer with unsaturated bond(s) that is copolymerizable with the vinyl chloride monomer, a graft copolymer obtained by graft copolymerization of a vinyl chloride monomer with a polymer, and the like can be used. These polymers may be used singly or in combinations of two or more.

Examples of the monomer with unsaturated bond(s) that is copolymerizable with the vinyl chloride monomer include α-olefins, vinyl esters, vinyl ethers, (meth)acrylates, aromatic vinyls, vinyl halides, and N-substituted maleimides. These monomers may be used singly or in combinations of two or more.

Examples of the α-olefins include ethylene, propylene, and butylene.

Examples of the vinyl esters include vinyl acetate and vinyl propionate.

Examples of the vinyl ethers include butyl vinyl ether and cetyl vinyl ether.

Examples of the (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl acrylate, and phenyl methacrylate.

Examples of the aromatic vinyls include styrene and α-methyl styrene.

Examples of the vinyl halides include vinylidene chloride and vinylidene fluoride.

Examples of the N-substituted maleimides include N-phenyl maleimide and N-cyclohexyl maleimide.

The polymer to which vinyl chloride is graft copolymerized is not limited as long as vinyl chloride can be graft copolymerized. Examples of the polymer include ethylene copolymers, acrylonitrile-butadiene copolymers, polyurethane, chlorinated polyethylene, and chlorinated polypropylene. These may be used singly or in combination of two or more.

Examples of the ethylene copolymers include ethylene-vinyl acetate copolymers, ethylene-vinyl acetate-carbon monoxide copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate-carbon monoxide copolymers, ethylene-methyl methacrylate copolymers, and ethylene-propylene copolymers. These polymers may be used singly or in combinations of two or more.

While the PVC may have any average degree of polymerization, it is preferably 400 to 3,000, as commonly employed, more preferably 600 to 1,500. The average degree of polymerization can be measured using the method described in JIS K 6720-2: 1999.

The method of polymerizing the PVC is not limited, and a conventionally known method such as aqueous suspension polymerization, block polymerization, solution polymerization, or emulsion polymerization can be used.

The resin composition for molding of the present invention contains an acrylic processing aid containing an acrylic resin having a weight average molecular weight of 500,000 to 5,000,000.

Examples of the acrylic resin include homopolymers of acrylic acid, methacrylic acid, and (meth)acrylates, and (meth)acrylic copolymers containing any of them.

Examples of the (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate. Examples of the (meth)acrylates also include n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate. The (meth)acrylic acid means acrylic acid or methacrylic acid. In the present invention, the acrylic resin is preferably a polymer of methyl (meth)acrylate (MMA).

Examples of comonomers copolymerized with (meth)acrylic acid, (meth)acrylate, or the like in the (meth)acrylic copolymers include styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylonitrile, and vinyl acetate.

These comonomers can be present in the form of a random copolymer, a graft copolymer, or a block copolymer in the acrylic resin.

The acrylic resin has a weight average molecular weight of 500,000 to 5,000,000.

With the weight average molecular weight within the range, a molded product having excellent surface smoothness can be obtained.

The lower limit of the weight average molecular weight is preferably 750,000 and the upper limit thereof is preferably 3,500,000.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured as molecular weights in terms of polystyrene by gel permeation chromatography (GPC).

The acrylic resin preferably has a glass transition temperature of 80° C. to 120° C.

With such an acrylic resin, a molded body having excellent surface properties can be obtained without impairing the heat resistance of the CPVC.

The acrylic resin preferably has a melting temperature of 90° C. to 150° C.

With such an acrylic resin, a molded body having excellent surface properties can be obtained without impairing the heat resistance of the CPVC.

The melting temperature can be measured by, for example, a method in accordance with JIS K 7210A (the temperature is elevated from 80° C. at 5° C./min, and the flow starting temperature is measured) using a device such as a flow tester.

The resin composition for molding of the present invention has an acrylic processing aid content of 0.2 to 10 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride. With the acrylic processing aid content in this range, the resulting molded body has improved surface smoothness, in particular low filtered waviness.

The lower limit of the acrylic processing aid content is preferably 0.8 parts by mass, more preferably 1.0 part by mass. The upper limit thereof is preferably 7.5 parts by mass, more preferably 5 parts by mass.

The acrylic processing aid content is preferably 150 to 650 parts by mass relative to 100 parts by mass of the thermal stabilizer.

The acrylic processing aid content is preferably 0.4 to 7.0% by mass in the entire resin composition for molding of the present invention.

The resin composition for molding of the present invention contains an impact resistance modifier.

The impact resistance modifier is used to improve the impact resistance of the resulting molded body. The impact resistance modifier contains a rubber component. The impact resistance modifier differs from the acrylic processing aid.

Examples of the impact resistance modifier include: a copolymer of a (meth)acrylate monomer component and a rubber component; and a silicone acrylic rubber containing a (meth)acrylate monomer component and an organosiloxane monomer component.

Examples of the (meth)acrylate monomer component include alkyl (meth)acrylates containing 1 or more but 12 or less carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethyl (meth)acrylate, and 2-ethylhexyl methacrylate. These monomer components may be used singly or in combination of two or more (e.g., three).

The (meth)acrylate monomer component content of the polymer constituting the impact resistance modifier is not limited, and is preferably 20 to 40% by mass, for example.

The rubber component may be a diene component or a non-diene component, and may be a homopolymer or a copolymer (including a bipolymer and a terpolymer). The copolymer may be any type of copolymer; the copolymer may be a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer.

Examples of the diene component include butadiene, isoprene, and chloroprene. Examples of the diene component also include copolymers containing a monomer component selected from the group consisting of a diene, an unsaturated nitrile, an α-olefin, and an aromatic vinyl. Specific examples include copolymers of an unsaturated nitrile and a diene (e.g., acrylonitrile-butadiene copolymer), copolymers of an aromatic vinyl and a diene (e.g., butadiene-styrene copolymer, styrene-isoprene copolymer), copolymers of an olefin and a diene (e.g., ethylene-propylene-diene copolymer).

The diene component content of the polymer constituting the impact resistance modifier is preferably 35 to 70% by mass, more preferably 50 to 65% by mass.

Examples of the non-diene component include polymers containing one or two or more monomer components selected from the group consisting of an olefin and an organosiloxane. Specific examples include olefin rubbers (e.g., ethylene-propylene rubber) and silicone acrylic rubbers.

More specifically, preferred impact resistance modifiers include methyl methacrylate-butadiene-styrene copolymers (MBS), acrylonitrile-butadiene-styrene copolymers (ABS), methyl methacrylate-acrylonitrile-butadiene-styrene copolymers (MABS), and methyl methacrylate-butadiene copolymers (MB).

Preferred impact resistance modifiers also include methyl methacrylate-acrylic/butadiene rubber copolymers, methyl methacrylate-acrylic/butadiene rubber-styrene copolymers, and methyl methacrylate-(acrylic/silicone complex) copolymers. The impact resistance modifier preferably contains a methyl methacrylate-butadiene-styrene copolymer and/or an acrylonitrile-butadiene-styrene copolymer.

Among the constituents of the impact resistance modifier, the resin contributing to the impact resistance effect preferably singly has a glass transition temperature of lower than 0° C. This enables improvement of the impact resistance without impairing the heat resistance of the resulting molded body.

The resin composition for molding of the present invention has an impact resistance modifier content of 0.5 to 8 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride. The impact resistance modifier contained within the range can further improve the impact resistance of the resulting molded body.

The lower limit of the impact resistance modifier content is preferably 3 parts by mass, more preferably 4 parts by mass. The upper limit thereof is preferably 8 parts by mass, more preferably 7.5 parts by mass.

The impact resistance modifier content of the entire resin molding composition for molding of the present invention is preferably 2.5 to 6.0% by mass.

In the resin composition for molding of the present invention, the ratio of the impact resistance modifier to the acrylic processing aid (impact resistance modifier/acrylic processing aid) is preferably 7.0 or less. When the ratio is within the range, a molded product having both satisfactory appearance and impact resistance can be obtained.

The impact resistance modifier/acrylic processing aid ratio is preferably 0.7 to 7.0, more preferably 0.7 to 4.0.

The impact resistance modifier is preferably in a particle form with a small average particle size. The impact resistance modifier particles preferably have an average particle size of about 0.1 to 200 μm.

The resin composition for molding of the present invention preferably further contains a thermal stabilizer.

In the present invention, the thermal stabilizer is preferably an organotin stabilizer. The thermal stabilizer preferably contains a calcium alkyl carboxylate and a zinc compound.

Examples of the organotin stabilizer include salts of alkyltins (e.g., methyltin, butyltin, octyltin), preferably dialkyltins and aliphatic monocarboxylic acids such as lauric acid or dicarboxylic acids such as maleic acid and phthalic acid. Specific examples of the organotin stabilizer include dibutyltin dilaurate, dioctyltin laurate, dibutyltin maleate, dibutyltin phthalate, dimethyltin bis(2-ethylhexyl thioglycolate), and alkyltin mercaptide such as dibutyltin mercaptide and dimethyltin mercaptide.

The thermal stabilizer containing a calcium alkyl carboxylate and a zinc compound contains no heavy metal, and thus, a heavy-metal free resin composition for molding can be obtained.

When this thermal stabilizer is used, hydrochloric acid produced by the pyrolysis of the chlorinated polyvinyl chloride immediately reacts with the zinc compound to form zinc chloride. Further, the growth of polyenes produced by the elimination of hydrochloric acid from the chlorinated polyvinyl chloride is stopped through bonding with calcium alkyl carboxylate. As a result, coloring is suppressed.

The produced zinc chloride, which has the property of accelerating the pyrolysis of the chlorinated polyvinyl chloride, reacts with calcium alkyl carboxylate to produce calcium chloride and zinc alkyl carboxylate in the present invention. As a result, the thermal stabilizer has a significant synergistic effect in that it suppresses the pyrolysis-accelerating effect of zinc chloride, while utilizing the effect of the zinc compound of rapidly capturing hydrochloric acid.

Examples of the calcium alkyl carboxylate include calcium salts of pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, cyclohexylpropionic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, arachidic acid, behenic acid, lignoceric acid, and montanic acid.

Among the above, a calcium alkyl carboxylate with 8 to 28 carbon atoms is preferably used.

Examples of the zinc compound include inorganic zinc compounds and organozinc compounds.

Examples of the inorganic zinc compounds include compounds including a carbonate, a chloride, a sulfate, an oxide, a hydroxide, a basic oxide, and a mixed oxide of zinc.

Examples of the organozinc compounds include alkyl zinc compounds such as di- and/or mono-alkyl zinc, zinc salts of organic aliphatic carboxylic acids, zinc salts of unsubstituted or substituted organic aromatic carboxylic acids, zinc organic phosphites, zinc salts of substituted or unsubstituted phenols, zinc salts of amino acids and derivatives thereof, and zinc salts of organic mercaptans.

Examples of organic aliphatic carboxylic acids forming the zinc salts of organic aliphatic carboxylic acids include montanic acid, rice bran fatty acids, behenic acid, erucic acid, stearic acid, oleic acid, linolic acid, rice fatty acids, ricinoleic acid, myristic acid, palmitic acid, lauric acid, lower fatty acids, octylic acid, isostearic acid, dimer acids, naphthenic acid, and acetic acid.

Examples of the organic aliphatic carboxylic acids also include dicarboxylic acids such as azelaic acid, sebacic acid, adipic acid, succinic acid, malonic acid, maleic acid, crotonic acid, malic acid, and tartaric acid, and monoesters thereof.

Examples of the organic aliphatic carboxylic acids also include citric acid and monoesters or diesters thereof, lactic acid, glycolic acid, thiodipropionic acid and monoesters thereof.

Examples of unsubstituted or substituted aromatic carboxylic acids forming the zinc salts of unsubstituted or substituted organic aromatic carboxylic acids include benzoic acid, o-, m- and p-toluylic acid, p-tert-butyl benzoic acid, p-hydroxybenzoic acid, salicylic acid, polybasic acids such as phthalic acid, meta-phthalic acid, terephthalic acid, and trimellitic acid, as well as monoesters or diesters thereof.

Examples of organic phosphites forming the zinc organic phosphites include acid phosphites, which are reaction products of fatty alcohols and phosphorus pentoxide. Specific examples of acid phosphites include butyl acid phosphite, octyl acid phosphite, stearyl acid phosphite, and behenyl acid phosphite.

Examples of substituted or unsubstituted phenols forming the zinc salts of substituted or unsubstituted phenols include phenols, cresols, xylol, octylphenol, nonylphenol, dinonylphenol, cyclohexylphenol, and phenylphenol. Examples of the substituted or unsubstituted phenols also include bisphenol A, bisphenol S, bisphenol F, esters of p-hydroxybenzoic acid, and esters of salicylic acid.

Examples of the amino acids and derivatives thereof include baked glutamic acid, glycine, and alanine.

Examples of organic mercaptans forming the zinc salts of organic mercaptans include lauryl mercaptan, thioglycolic acid and esters thereof, mercaptopropionic acid and esters thereof, thiomalic acid and monoesters or diesters thereof.

The thermal stabilizer, which contains a calcium alkyl carboxylate and a zinc compound, is preferably a mixture of the calcium alkyl carboxylate and the zinc compound.

The thermal stabilizer may be in the form of a powder or granular material, for example. The thermal stabilizer made into such a form can be used as a single-pack thermal stabilizer.

When the thermal stabilizer is in the form of a particulate material, the particle size can be adjusted as appropriate, depending on the purpose. Generally, the average particle size is preferably 50 μm to 5 mm, particularly preferably 70 μm to 2 mm.

The thermal stabilizer in the form of the granular material can be produced using a known granulation method, for example, extrusion granulation, spray granulation, rotating disk granulation, rolling granulation, or compression granulation.

The thermal stabilizer preferably has a loss in quantity on heating at 230° C. of less than 5% by mass.

When the loss in quantity on heating at 230° C. is 5% by mass or more, bubbles may be included inside the molded product to result in poor strength, or a streak-like pattern may be formed near the surface of the molded product to result in a defective appearance.

The loss in quantity on heating at 230° C. is more preferably less than 3% by mass.

The lower limit thereof is not limited, but is preferably 0.1% by mass.

The loss in quantity on heating at 230° C. can be measured using a thermogravimetric measurement (TG) apparatus.

The thermal stabilizer contains a calcium alkyl carboxylate and a zinc compound. The mixing ratio of the calcium alkyl carboxylate to the zinc compound (calcium alkyl carboxylate:zinc compound) is preferably 9:1 to 4:6, more preferably 8:2 to 5:5.

The resin composition for molding of the present invention preferably has a thermal stabilizer content of 0.4 to 10 parts by mass, more preferably 0.6 to 7 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride. When the thermal stabilizer is contained within this range, the thermal stability can be more improved, and the molded body can maintain good appearance.

When the thermal stabilizer is one containing a calcium alkyl carboxylate and a zinc compound, a heavy metal-free resin composition for molding can be obtained. As used herein, the term “heavy metal” refers to a metal with a high density, and generally, a metal with a density of 4 to 5 g/cm³ or more. The term “heavy metal-free” means that the heavy metal content is 1,000 ppm or less. The heavy metal content is preferably 100 ppm or less.

Examples of such heavy metals include transition metals other than scandium, for example, Mn, Ni, Fe, Cr, Co, Cu, and Au. Such heavy metals also include metals of p-block elements in period 4 or less (e.g., Sn, Pb, and Bi), Cd, and Hg.

The resin composition for molding of the present invention preferably further contains an antioxidant.

Examples of the antioxidant include phenolic antioxidants, phosphate antioxidants, sulfur antioxidants, and amine antioxidants. These antioxidants may be used singly or in combinations of two or more. Among the above, a phenolic antioxidant is preferred, and in particular, a hindered phenolic antioxidant is preferred.

Examples of the hindered phenolic antioxidant include 2,6-di-t-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-t-butyl-4-hydroxyphenyl)propionate, distearyl (3,5-t-butyl-4-hydroxybenzyl)phosphonate, 2,2′-methylenebis(4-methyl-6-t-butylphenol), 2,2′-methylenebis(4-ethyl-6-t-butylphenol), bis[3,3-bis(4-hydroxy-3-t-butylphenyl)butyric acid]glycol ester, 4,4′-butylidenebis(6-t-butyl-m-cresol), 2,2′-ethylidenebis(4,6-di-t-butylphenol), 2,2′-ethylidenebis(4-sec-butyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, bis[2-t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl] terephthalate, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl) isocyanurate, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate, pentaerythrityl-tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2-t-butyl-4-methyl-6-(2′-acryloyloxy-3′-t-butyl-5′-methylbenzyl)phenol, 3,9-bis(1′,1′-dimethyl-2′-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, and bis[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate]. Among the above, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, pentaerythrityl-tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and the like are preferred. These hindered phenolic antioxidants can be used singly or in combinations of two or more.

The antioxidant preferably has a loss in quantity on heating at 200° C. of less than 5% by mass.

When the loss in quantity on heating at 200° C. is 5% by mass or more, bubbles may be included inside the molded product to result in poor strength, or a streak-like pattern may be formed near the surface of the molded product to result in a defective appearance.

The loss in quantity on heating at 200° C. is more preferably less than 3% by mass.

The resin composition for molding of the present invention preferably has an antioxidant content of 0.1 to 3 parts by mass, more preferably 0.2 to 2.5 parts by mass, relative to 100 parts by mass of the chlorinated polyvinyl chloride. When the antioxidant is contained within this range, a molded product with little coloration due to yellowing can be obtained.

The resin composition for molding of the present invention preferably further contains an auxiliary stabilizer. When the auxiliary stabilizer is contained, thermal stability can be further improved.

A heavy metal-free auxiliary stabilizer can be used as the auxiliary stabilizer. Examples thereof include organic acid salts, epoxy compounds, phosphorous compounds, metal hydroxides, sodium adipate, glycidyl (meth)acrylate copolymers, oxetanyl compounds, vinyl ether compounds, and zeolite compounds.

Examples of the epoxy compounds include epoxidized soybean oil, epoxidized linseed oil, epoxidized tetrahydrophthalate, epoxidized polybutadiene, and bisphenol A-type epoxy compounds.

Examples of the phosphorous compounds include organophosphorous compounds, phosphites, and phosphates.

Examples of the metal hydroxides include calcium hydroxide and sodium hydroxide.

These auxiliary stabilizers may be used singly or in combinations of two or more. Note that the auxiliary stabilizer differs from the calcium alkyl carboxylate and the zinc compound.

These auxiliary stabilizers may be used singly or in combinations of two or more. Note that the auxiliary stabilizer differs from the calcium alkyl carboxylate and the zinc compound.

Further, the auxiliary stabilizer preferably has a loss in quantity on heating at 200° C. of less than 5% by mass.

The resin composition for molding of the present invention may be optionally mixed with additives such as lubricants, processing aids, heat resistance improvers, ultraviolet absorbents, light stabilizers, fillers, thermoplastic elastomers, and pigments.

Examples of the lubricants include internal lubricants and external lubricants. An internal lubricant is used to reduce the fluid viscosity of the molten resin during molding to prevent the generation of frictional heat. Examples of the internal lubricants include, but are not limited to, butyl stearate, lauryl alcohol, stearyl alcohol, glycerol monostearate, stearic acid, and bisamide. These internal lubricants may be used singly or in combinations of two or more.

The lubricant preferably has a loss in quantity on heating at 200° C. of less than 5% by mass.

The external lubricant is used to improve the slip effect between metal surfaces and the molten resin during molding. Examples of the external lubricants include, but are not limited to, paraffin wax, polyolefin waxes such as polyethylene lubricants, ester waxes such as fatty acid ester lubricants, and montanic acid wax. These external lubricants may be used singly or in combinations of two or more.

Examples of the heat resistance improvers include, but are not limited to, α-methylstyrene resins and N-phenyl maleimide resins.

Examples of the light stabilizers include, but are not limited to, hindered amine light stabilizers.

Examples of the ultraviolet absorbents include, but are not limited to, salicylate ultraviolet absorbents, benzophenone ultraviolet absorbents, benzotriazole ultraviolet absorbents, and cyanoacrylate ultraviolet absorbents.

Examples of the pigments include, but are not limited to, organic pigments such as azo pigments, phthalocyanine pigments, threne pigments, and dye lake pigments; and inorganic pigments such as titanium dioxide and other oxide pigments, sulfide/selenide pigments, and ferrocyanide pigments.

A plasticizer may be added to the resin composition for molding of the present invention to improve processability during molding. The use of a large amount of plasticizer, however, is not so desirable because it may reduce the thermal stability of the molded body. Examples of the plasticizers include, but are not limited to, dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate.

A thermoplastic elastomer may be added to the resin composition for molding of the present invention to improve workability. Examples of the thermoplastic elastomers include, but are not limited to, nitrile thermoplastic elastomers, olefin thermoplastic elastomers, vinyl chloride thermoplastic elastomers, styrene thermoplastic elastomers, urethane thermoplastic elastomers, polyester thermoplastic elastomers, and polyamide thermoplastic elastomers.

Examples of the nitrile thermoplastic elastomers include acrylonitrile-butadiene copolymers (NBR).

Examples of the olefin thermoplastic elastomers include ethylene thermoplastic elastomers such as ethylene-vinyl acetate copolymers (EVA) and ethylene-vinyl acetate-carbon monoxide copolymers (EVACO).

Examples of the vinyl chloride thermoplastic elastomers include vinyl chloride-vinyl acetate copolymers and vinyl chloride-vinylidene chloride copolymers.

These thermoplastic elastomers may be used singly or in combinations of two or more.

The resin composition for molding of the present invention is preferably free from a β-diketone. A β-diketone is a component contained in conventional thermal stabilizers to improve thermal stability. When, however, a thermal stabilizer containing a β-diketone is used, the appearance of a molded body tends to be impaired in the production of the molded body by molding a resin composition by extrusion molding or injection molding. For example, streaks of a yellow to reddish brown color with a thickness of approximately 0.1 to 1 mm may be formed on the surface of the molded body, in parallel with the direction of flow of the resin. A molded body having such an impaired appearance is a defective product. In particular, the use of a die that has been used for long hours tends to produce such a defective product. In accordance with the present invention, however, a resin composition for molding having excellent thermal stability can be provided without using a thermal stabilizer containing a β-diketone.

The resin composition for molding of the present invention may be produced using, for example, a method including the steps of: preparing a chlorinated polyvinyl chloride by preparing a suspension of a polyvinyl chloride in an aqueous medium in a reaction vessel, introducing chlorine into the reaction vessel, and chlorinating the polyvinyl chloride using any conventionally known method; and then adding predetermined amounts of an acrylic processing aid containing an acrylic resin having a weight average molecular weight of 500,000 to 5,000,000 and an impact resistance modifier to the chlorinated polyvinyl chloride, followed by mixing.

In the step of preparing the chlorinated polyvinyl chloride, the reaction vessel used may be a commonly used vessel such as a glass-lined stainless steel reaction vessel or titanium reaction vessel, for example.

The method of preparing the suspension of the polyvinyl chloride in an aqueous medium is not limited. For example, a cake-like PVC obtained by subjecting a polymerized PVC to monomer removal treatment may be used, a dried PVC may be resuspended in an aqueous medium, or a suspension obtained by removing any substances undesired for the chlorination reaction from the polymerization system may be used. It is preferred to use a cake-like resin obtained by subjecting a polymerized PVC to monomer removal treatment.

The aqueous medium used may be ion-exchange-treated pure water, for example. While the amount of the aqueous medium is not limited, generally, it is preferably 150 to 400 parts by mass based on 100 parts by mass of the PVC.

Chlorine to be introduced into the reaction vessel may be either liquid chlorine or gaseous chlorine. The use of liquid chlorine is efficient in that a large amount of chlorine can be charged into the reaction vessel in a short period of time. Chlorine may be added in the course of reaction to adjust the pressure or supply chlorine. At this time, gaseous chlorine in addition to liquid chlorine may be blown into the reaction vessel, as required. It is preferred to use chlorine after purging 5 to 10% by mass of chlorine from a cylinder.

While the gauge pressure in the reaction vessel is not limited, it is preferably from 0.3 to 2 MPa, because the higher is the chlorine pressure, the more readily the chlorine will penetrate into the PVC particles.

The method of chlorinating the PVC in the suspended state is not limited. Examples of chlorination methods include a method in which the excitation of bonding of the PVC and chlorine is brought about by thermal energy to accelerate the chlorination (hereinafter referred to as heat chlorination); and a method in which light energy such as ultraviolet light is applied to accelerate the chlorination by photoreaction (hereinafter referred to as photo-chlorination). The heating method in the chlorination by thermal energy is not limited, and for example, heating with an external jacket from the reactor walls is effective. The use of light energy such as ultraviolet light requires an apparatus capable of light energy irradiation such as ultraviolet irradiation under high temperature and high pressure conditions. In the case of photo-chlorination, the chlorination reaction temperature is preferably 40° C. to 80° C.

Preferred among the above chlorination methods is a heat chlorination method involving no ultraviolet irradiation. Preferred is a method in which the excitation of bonding of the polyvinyl chloride and chlorine is brought about by heat alone or by heat and hydrogen peroxide to accelerate the chlorination reaction.

In the case of the chlorination reaction by light energy, the amount of light energy needed to chlorinate the PVC is greatly affected by the distance between the PVC and the light source. Thus, the amount of received energy is different inside and on the surface of the PVC particles, so that chlorination does not occur uniformly. As a result, a CPVC with reduced uniformity is obtained. In contrast, with the method of chlorination by heat without ultraviolet irradiation, a more uniform chlorination reaction occurs to produce a CPVC with increased uniformity.

The chlorination by heat alone is preferably performed at a temperature of 70° C. to 140° C. When the temperature is excessively low, the rate of chlorination will decrease. When the temperature is excessively high, dehydrochlorination reaction will occur along with the chlorination reaction, which causes coloration of the resulting CPVC. The heating temperature is more preferably 100° C. to 135° C. The heating method is not limited, and heating may be performed with an external jacket from the reaction vessel walls, for example.

In the chlorination, hydrogen peroxide is preferably further added to the suspension. The addition of hydrogen peroxide can improve the rate of chlorination. Hydrogen peroxide is preferably added in an amount of 5 to 500 ppm to the PVC per hour of the reaction time. When the amount of hydrogen peroxide added is excessively small, the effect of improving the rate of chlorination cannot be obtained. When the amount of hydrogen peroxide added is excessively large, the thermal stability of the CPVC will decrease.

When hydrogen peroxide is added as described above, the rate of chlorination is improved, so that the heating temperature can be set relatively low. The heating temperature may be 65° C. to 110° C., for example.

During the chlorination, it is preferred to perform chlorination at a chlorine consumption rate of 0.010 to 0.015 kg/PVC-Kg·5 min after the chlorine content reaches a value that is five percentage points by mass lower than the final chlorine content, and further perform chlorination at a chlorine consumption rate of 0.005 to 0.010 kg/PVC-Kg·5 min after the chlorine content reaches a value that is three percentage points by mass lower than the final chlorine content. As used herein, the term “chlorine consumption rate” refers to the amount of chlorine consumed in 5 minutes per kilogram of the raw material PVC.

When chlorination is performed using the above-described method, a CPVC having less nonuniformity in the chlorinated state and having excellent thermal stability can be obtained.

The method of producing the resin composition for molding of the present invention includes the subsequent step of adding predetermined amounts of an acrylic processing aid containing an acrylic resin having a weight average molecular weight of 500,000 to 5,000,000 and an impact resistance modifier, and optionally a thermal stabilizer and an antioxidant, to the chlorinated polyvinyl chloride, followed by mixing.

The method of mixing the thermal stabilizer and the antioxidant is not limited, and may be a method using hot blending or cold blending, for example.

In accordance with the structure of the present invention described above, a resin composition for molding having excellent thermal stability and free of heavy metals such as lead, cadmium, and tin can be provided.

Further, in accordance with another aspect of the present invention, a molded body molded from the resin composition for molding of the present invention is provided. Such a molded body is also encompassed by the present invention.

The molding method may be any conventionally known molding method, for example, extrusion molding or injection molding.

The molded body of the present invention is heavy metal-free, as with the resin composition for molding of the present invention, and thus, has the advantage of having no adverse effects on the environment, has excellent thermal stability, and has a satisfactory appearance. The molded body of the present invention can therefore be suitably used in applications such as building components, pipes and engineering plastics, and housing materials.

The molded body of the present invention preferably has a surface roughness (Rmax) of 1.0 μm or less.

The molded body of the present invention preferably has a filtered waviness center line average (WcA) at the outer surface of 5.0 μm or less. Such a molded body has less surface unevenness and less variation in thickness. In the present invention, not only the surface roughness but also the filtered waviness center line average is small. Thus, when used as a pipe or the like, the molded body has less friction with flowing water and thus can increase the velocity of flow.

The surface roughness (Rmax) can be measured by a method in accordance with JIS B 0601. The filtered waviness center line average (WcA) can be measured by a method in accordance with JIS B 0610.

Advantageous Effects of Invention

The present invention can provide a resin composition for molding that can provide a molded body having excellent thermal stability, high impact resistance, and high surface smoothness. The present invention can also provide a molded body including the resin composition for molding.

DESCRIPTION OF EMBODIMENTS

The present invention will be hereinafter described in more detail with reference to examples; however, the invention should not be construed as being limited to these examples.

Example 1

(Preparation of Chlorinated Polyvinyl Chloride)

A glass-lined reaction vessel with an internal volume of 300 L was charged with 200 kg of ion-exchange water and 56 kg of a polyvinyl chloride with a degree of polymerization of 1,000. The mixture was stirred, and water was further added to the reaction vessel to disperse the mixture in the water. The pressure was subsequently reduced to remove oxygen from the reaction vessel, and the temperature was simultaneously elevated to 90° C.

Chlorine was then supplied into the reaction vessel so that the chlorine partial pressure would be 0.4 MPa, and the chlorination reaction was performed while adding 0.2% by mass hydrogen peroxide at a rate of 1 part by mass per hour (320 ppm/hour). The reaction was continued until the chlorine content of the chlorinated polyvinyl chloride reached 61% by mass. When the chlorine content of the chlorinated polyvinyl chloride reached 61% by mass (five percentage points by mass lower than the final chlorine content), the amount of 0.2% by mass hydrogen peroxide added was reduced to 0.1 parts by mass per hour (200 ppm/hour), and the average chlorine consumption rate was adjusted to 0.012 kg/PVC-kg·5 min, and then the chlorination was allowed to proceed. Further, when the chlorine content reached 63% by mass (three percentage points by mass lower than the final chlorine content), the amount of 0.2% by mass hydrogen peroxide added was reduced to 150 ppm/hour, and the average chlorine consumption rate was adjusted to 0.008 kg/PVC-kg·5 min, and then the chlorination was allowed to proceed. In this way, a chlorinated polyvinyl chloride having a chlorine content of 67.3% by mass was obtained. The chlorine content of the chlorinated polyvinyl chloride was measured in accordance with JIS K 7229.

The gelling time of the chlorinated polyvinyl chloride was measured by the following method.

(Gelling Time Measurement)

A compound sample was prepared by adding 1.2 parts by mass of a thermal stabilizer, 1.0 part by mass of a polyethylene lubricant, 0.5 parts by mass of a polyethylene oxide lubricant, and 5.5 parts by mass of an impact resistance modifier to 100 parts by mass of the chlorinated polyvinyl chloride. The thermal stabilizer, polyethylene lubricant, polyethylene oxide lubricant, impact resistance modifier used were as follows.

Thermal stabilizer (available from Nitto Kasei Co., Ltd., TVS #1380) Polyethylene lubricant (available from Mitsui Chemicals, Inc., Hiwax 220MP)

Polyethylene oxide lubricant (available from Honeywell International Inc., A-C 316A)

Impact resistance modifier (available from Kaneka Corporation, Kane Ace M-511)

Subsequently, 59 g of the compound sample was put in Labo PlastoMill (available from Toyo Seiki Seisaku-Sho, Ltd., 4C150) at a temperature of 180° C. and pre-heated for 80 seconds. The rotor was then rotated at a frequency of 30 rpm. The time at which the motor torque reached its maximum was determined as the gelling time.

(Preparation of Chlorinated Polyvinyl Chloride Composition)

To 100 parts by mass of the obtained chlorinated polyvinyl chloride (degree of polymerization: 1,000) were added 1.5 parts by mass of polymethyl methacrylate (available from Mitsubishi Rayon Co., Ltd., weight average molecular weight: 800,000, glass transition temperature: 75° C., melting temperature: 136° C.) as an acrylic processing aid and 5.5 parts by mass of an impact resistance modifier. Furthermore, 1.5 parts by mass of a thermal stabilizer and 0.5 parts by mass of pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (hindered phenolic antioxidant, Irganox 1010, available from BASF, loss in quantity on heating at 200° C.: 1.0% by mass) as an antioxidant were added, followed by mixing. The impact resistance modifier used was MBS-1 (methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate component content: 25% by mass, diene component content: 55% by mass, average particle size: 0.3 μm) resin (available from LG Chem Ltd., glass transition temperature of butadiene alone: −93° C.). The thermal stabilizer (organotin stabilizer) used was dimethyltin bis(2-ethylhexyl thioglycolate).

Then, 2.0 parts by mass of a polyethylene lubricant (available from Mitsui Chemicals, Inc., Hiwax 220MP), 0.3 parts by mass of a fatty acid ester lubricant (available from Emery Oleochemicals Japan Ltd., LOXIOL G-32), and 6.0 parts by mass of titanium dioxide (available from Ishihara Sangyo Kaisha, Ltd., TIPAQUE CR-90) were added. This was followed by uniform mixing in a super mixer to give a chlorinated polyvinyl chloride composition.

(Preparation of Extrudate)

The obtained chlorinated polyvinyl chloride composition was fed into a twin-screw counter-rotating conical extruder with a diameter of 50 mm (Osada Seisakusho; “SLM-50”) to prepare a pipe-shaped extrudate with an internal diameter of 20 mm and a thickness of 3 mm at a resin temperature of 209.8° C., a back pressure of 291.0 kg/cm², and an extrusion amount of 24.3 kg/hr.

Examples 2 to 14 and Comparative Examples 1 to 6

A chlorinated polyvinyl chloride composition and an extrudate were prepared as in Example 1 except that polymethyl methacrylate having a weight average molecular weight (Mw) and a melting temperature as shown in Table 1 and an impact resistance modifier were used in the amounts shown in Table 1. In Example 11, the impact resistance modifier used was ABS (available from Galata Chemicals, Blendex 338, acrylonitrile-butadiene-styrene copolymer) resin.

In Examples 12 and 13, calcium stearate and zinc stearate were used instead of dimethyltin bis(2-ethylhexyl thioglycolate).

In Example 14, MBS-2 (methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate component content: 25% by mass, diene component content: 40% by mass, average particle size: 0.3 μm) was used instead of MBS-1.

The conditions for extrusion molding were changed as shown in Table 1.

Example 15

A chlorinated polyvinyl chloride composition and an extrudate were prepared as in Example 1 except that a chlorinated polyvinyl chloride having a gelling time shown in Table 1 was used.

<Evaluation>

The chlorinated polyvinyl chloride compositions and extrudates obtained in the examples and the comparative examples were evaluated as follows. Table 1 shows the results.

[Evaluation of Chlorinated Polyvinyl Chloride Composition]

<Mechanical Properties (Izod Impact Strength, Tensile Strength, Tensile Modulus of Elasticity, and Thermal Deformation Temperature)>

The obtained chlorinated polyvinyl chloride composition was fed to two 8-inch rolls, and kneaded at 205° C. for 3 minutes to prepare 1.0-mm-thick sheets. The obtained sheets were layered, preheated with a press at 205° C. for 3 minutes, and then pressurized for 4 minutes to obtain a 3-mm-thick press plate. The obtained press plate was cut into specimens by machining. With these specimens, the Izod impact strength was measured in accordance with ASTM D256, and the tensile strength and tensile modulus of elasticity were measured in accordance with ASTM D638. The thermal deformation temperature was measured under a load of 186 N/cm² in accordance with ASTM D648. The thermal deformation temperature was measured after annealing the obtained press plate in a gear oven at 90° C. for 24 hours.

<Vicat Softening Temperature>

The Vicat softening temperature was measured by a method in accordance with JIS K 7206:2016 (Plastics-Thermoplastic materials-Determination of Vicat softening temperature, B50 method).

[Evaluation of Molded Body]

<Appearance Observation>

The surface state of the pipe-shaped extrudate was visually observed to evaluate the presence or absence of scorching (discoloration).

<Surface Roughness>

The surface roughness (Rmax) was measured using a surface roughness measuring instrument (available from Tokyo Seimitsu Co., Ltd., SURFCOM 480A) by a method in accordance with JIS B 0601. The measurement was performed at an evaluation length of 0.3 mm, a measurement speed of 0.3 mm/sec, and a cut-off value of 0.08 mm.

<Filtered Waviness>

The filtered waviness center line average (filtered center line waviness, WcA) of the outer surface was measured using a surface roughness measuring instrument (available from Tokyo Seimitsu Co., Ltd., SURFCOM 480A) by a method in accordance with JIS B 0601. The measurement was performed at an evaluation length of 30 mm, a measurement speed of 3 mm/sec, and a cut-off value of 0.25 to 8 mm.

TABLE 1 Examples 1 2 3 4 5 6 Composition Chlorinated polyvinyl chloride Amount 100 100 100 100 100 100 (parts by mass) Acrylic processing aid Gelling time (seonds) 127 127 127 127 127 127 (PMMA) Mw: 800,000 (melting 1.5 — — — — — temperature: 136° C.) Mw: 1,100,000 (melting — 1.5 — — — — temperature: 130° C.) Mw: 1,400,000 (melting — — 1.5 — — — temperature: 118° C.) Mw: 1,450,000 (melting — — — 1.5 — — temperature: 114° C.) Mw: 2,400,000 (melting — — — — 1.5 — temperature: 122° C.) Mw: 3,100,000 (melting — — — — — 1.5 temperature: 119° C.) Mw: 250,000 (melting — — — — — — temperature: 133° C.) Mw: 6,000,000 (melting — — — — — — temperature: 103° C.) Impact resistance modifier MBS-1 5.5 5.5 5.5 5.5 5.5 5.5 MBS-2 — — — — — — ABS — — — — — — Mass ratio (impact resistance 3.7 3.7 3.7 3.7 3.7 3.7 improver/acrylic processing aid) Organotin stabilizer 1.5 1.5 1.5 1.5 1.5 1.5 Calcium stearate — — — — — — Zinc stearate — — — — — — Hindered phenolic antioxidant 0.5 0.5 0.5 0.5 0.5 0.5 Polyethylene lubricant 2.0 2.0 2.0 2.0 2.0 2.0 Fatty acid ester lubricant 0.3 0.3 0.3 0.3 0.3 0.3 Titanium dioxide 6.0 6.0 6.0 6.0 6.0 6.0 Mass ratio (impact resistance 4.69% 4.69% 4.69% 4.69% 4.69% 4.69% improver/entire composition) Mass ratio (acrylic processing 1.28% 1.28% 1.28% 1.28% 1.28% 1.28% aid/entire composition) Extrusion Temperature (° C.) 209.8 210.0 212.0 211.0 212.0 213.0 molding Back pressure (kg/cm²) 291.0 293.5 300.0 291.0 312.0 314.0 conditions Extruding amount (kg/hr) 24.3 25.1 22.7 22.3 23.3 22.9 Evaluation Mechanical properties IZOD test (J/m) 104.7 111.6 151.1 152.3 131.4 146.2 (chlorinated Tensile strength (MPa) 52.59 53.13 52.3 53.0 52.7 53.1 polyvinyl Tensile modulus of 2625 2612 2708 2720 2781 2770 chloride elasticity (MPa) composition) Thermal deformation 112.9 112.7 113.7 113.7 113.7 113.7 temperature (° C.) Vicat softening 115.3 115.5 115.7 115.3 114.9 115.6 temperature (° C.) Evaluation Apparance Scorching None None None None None None (molded body) Surface roughness Rmax (μm) 0.73 0.7 0.9 0.98 0.54 1.06 Filtered center line waviness WcA (μm) 1.21 1.09 0.72 1.03 0.73 0.65 Examples 7 8 9 10 11 Composition Chlorinated polyvinyl chloride Amount 100 100 100 100 100 (parts by mass) Acrylic processing aid Gelling time (seonds) 127 127 127 127 127 (PMMA) Mw: 800,000 (melting 0.5 8 1.5 1.5 15 temperature: 136° C.) Mw: 1,100,000 (melting — — — — — temperature: 130° C.) Mw: 1,400,000 (melting — — — — — temperature: 118° C.) Mw: 1,450,000 (melting — — — — — temperature: 114° C.) Mw: 2,400,000 (melting — — — — — temperature: 122° C.) Mw: 3,100,000 (melting — — — — — temperature: 119° C.) Mw: 250,000 (melting — — — — — temperature: 133° C.) Mw: 6,000,000 (melting — — — — — temperature: 103° C.) Impact resistance modifier MBS-1 5.5 5.5 3 7 — MBS-2 — — — — — ABS — — — — 5.5 Mass ratio (impact resistance 11.0 0.7 2.0 4.7 3.7 improver/acrylic processing aid) Organotin stabilizer 1.5 1.5 1.5 1.5 1.5 Calcium stearate — — — — — Zinc stearate — — — — — Hindered phenolic antioxidant 0.5 0.5 0.5 0.5 0.5 Polyethylene lubricant 2.0 2.0 2.0 2.0 2.0 Fatty acid ester lubricant 0.3 0.3 0.3 0.3 0.3 Titanium dioxide 6.0 6.0 6.0 6.0 6.0 Mass ratio (impact resistance 4.73% 4.44% 2.61% 5.89% 4.69% improver/entire composition) Mass ratio (acrylic processing 0.43% 6.46% 1.31% 1.26% 1.28% aid/entire composition) Extrusion Temperature (° C.) 208.7 212.5 207.0 215.0 210.1 molding Back pressure (kg/cm²) 281.0 310.0 265.0 320.0 285.0 conditions Extruding amount (kg/hr) 25.5 21.5 25.1 19.8 23.2 Evaluation Mechanical properties IZOD test (J/m) 133.3 111.1 62 254 99.6 (chlorinated Tensile strength (MPa) 52.4 52.4 56.0 49.0 51.8 polyvinyl Tensile modulus of 2671 2632 2694 2560 2619 chloride elasticity (MPa) composition) Thermal deformation 113.5 113.3 113.5 112.5 112.7 temperature (° C.) Vicat softening 115.9 115.2 115.2 115.3 115.1 temperature (° C.) Evaluation Apparance Scorching None None None None None (molded body) Surface roughness Rmax (μm) 1.33 0.5 0.76 1.25 0.76 Filtered center line waviness WcA (μm) 1.87 0.99 1.26 1.30 1.19 Examples Comparative Examples 12 13 14 15 1 Composition Chlorinated polyvinyl chloride Amount 100 100 100 100 100 (parts by mass) Acrylic processing aid Gelling time (seonds) 127 127 127 160 127 (PMMA) Mw: 800,000 (melting 15 — 1.5 1.5 — temperature: 136° C.) Mw: 1,100,000 (melting — — — — — temperature: 130° C.) Mw: 1,400,000 (melting — — — — — temperature: 118° C.) Mw: 1,450,000 (melting — — — — — temperature: 114° C.) Mw: 2,400,000 (melting — — — — — temperature: 122° C.) Mw: 3,100,000 (melting — — — — — temperature: 119° C.) Mw: 250,000 (melting — — — — 1.5 temperature: 133° C.) Mw: 6,000,000 (melting — — — — — temperature: 103° C.) Impact resistance modifier MBS-1 5.5 5.5 5.5 5.5 MBS-2 — — 5.5 — — ABS — — — — — Mass ratio (impact resistance 3.7 3.7 3.7 3.7 3.7 improver/acrylic processing aid) Organotin stabilizer — — 1.5 1.5 1.5 Calcium stearate 1.5 1.5 — — — Zinc stearate 1.0 1.0 — — — Hindered phenolic antioxidant 0.5 0.5 0.5 0.5 0.5 Polyethylene lubricant 2.0 2.0 2.0 2.0 2.0 Fatty acid ester lubricant 0.3 0.3 0.3 0.3 0.3 Titanium dioxide 6.0 6.0 6.0 6.0 6.0 Mass ratio (impact resistance 4.65% 4.65% 4.69% 4.69% 4.69% improver/entire composition) Mass ratio (acrylic processing 1.27% 1.27% 1.28% 1.28% 1.28% aid/entire composition) Extrusion Temperature (° C.) 209.5 210.3 209.0 209.0 209.0 molding Back pressure (kg/cm²) 283.3 290.6 291.0 293.0 282.9 conditions Extruding amount (kg/hr) 25.3 24.7 24.5 23.6 24.0 Evaluation Mechanical properties IZOD test (J/m) 124.2 118.7 104 104 94.3 (chlorinated Tensile strength (MPa) 52.2 52.9 52 52.5 52.7 polyvinyl Tensile modulus of 2598 2633 2627 2660 2591 chloride elasticity (MPa) composition) Thermal deformation 113.4 112.5 112 113 113.7 temperature (° C.) Vicat softening 115.6 115 115.3 115.8 115.1 temperature (° C.) Evaluation Apparance Scorching None None None None None (molded body) Surface roughness Rmax (μm) 0.75 0.76 0.8 1.92 3.3 Filtered center line waviness WcA(μm) 1.19 1.25 1.50 2.40 8.1 Comparative Examples 2 3 4 5 6 Composition Chlorinated polyvinyl chloride Amount 100 100 100 100 100 (parts by mass) Acrylic processing aid Gelling time (seonds) 127 127 127 127 127 (PMMA) Mw: 800,000 (melting — 0.1 12 1.5 15 temperature: 136° C.) Mw: 1,100,000 (melting — — — — — temperature: 130° C.) Mw: 1,400,000 (melting — — — — — temperature: 118° C.) Mw: 1,450,000 (melting — — — — — temperature: 114° C.) Mw: 2,400,000 (melting — — — — — temperature: 122° C.) Mw: 3,100,000 (melting — — — — — temperature: 119° C.) Mw: 250,000 (melting — — — — — temperature: 133° C.) Mw: 6,000,000 (melting 1.5 — — — — temperature: 103° C.) Impact resistance modifier MBS-1 5.5 55 5.5 0.3 10 MBS-2 — — — — — ABS — — — — — Mass ratio (impact resistance 3.7 55.0 0.5 0.2 6.7 improver/acrylic processing aid) Organotin stabilizer 1.5 1.5 1.5 1.5 1.5 Calcium stearate — — — — — Zinc stearate — — — — — Hindered phenolic antioxidant 0.5 05 0.5 0.5 0.5 Polyethylene lubricant 2.0 2.0 2.0 2.0 2.0 Fatty acid ester lubricant 0.3 0.3 0.3 0.3 0.3 Titanium dioxide 6.0 6.0 6.0 6.0 6.0 Mass ratio (impact resistance 4.69% 4.75% 4.30% 0.27% 8.21% improver/entire composition) Mass ratio (acrylic processing 1.28% 0.09% 9.39% 1.34% 1.23% aid/entire composition) Extrusion Temperature (° C.) 218.0 208.4 220.0 205.9 221.0 molding Back pressure (kg/cm²) 380.0 269.0 388.0 247.0 374.0 conditions Extruding amount (kg/hr) 21.0 25.8 19.5 25.4 15.3 Evaluation Mechanical properties IZOD test (J/m) 152.6 133.3 120 30 630 (chlorinated Tensile strength (MPa) 53.6 524 522 56.9 46.0 polyvinyl Tensile modulus of 2801 2671 2685 2681 2504 chloride elasticity (MPa) composition) Thermal deformation 113.5 113.5 112.8 113.1 113 temperature (° C.) Vicat softening 114.9 115.9 115.4 115 115.7 temperature (° C.) Evaluation Apparance Scorching Occured None Occured None Occured (molded body) Surface roughness Rmax (μm) 0.6 2.8 0.2 1.38 2.8 Filtered center line waviness WcA (μm) 2 3.40 0.40 227 4.90

INDUSTRIAL APPLICABILITY

The present invention can provide a resin composition for molding that can provide a molded body having excellent thermal stability, high impact resistance, and high surface smoothness. The present invention can also provide a molded body including the resin composition for molding. 

The invention claimed is:
 1. A resin composition for molding comprising: a chlorinated polyvinyl chloride; an acrylic processing aid; and an impact resistance modifier, the acrylic processing aid comprising an acrylic resin having a weight average molecular weight of 1,100,000 to 2,400,000, a diene component content of a polymer constituting the impact resistance modifier is 35 to 65% by mass, the resin composition comprising the acrylic processing aid in an amount of 0.2 to 10 parts by mass and the impact resistance modifier in an amount of 5.5 to 8.0 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride, and the chlorinated polyvinyl chloride having structural units (a) to (c) represented by the following formulae (a) to (c): —CCl₂—  (a), —CHCl—  (b), —CH₂—  (c), wherein a proportion of the structural unit (a) is 17.5 mol % or less, a proportion of the structural unit (b) is 46.0 mol % or more, and a proportion of the structural unit (c) is 37.0 mol % or less, relative to a total number of moles of the structural units (a), (b), and (c).
 2. The resin composition for molding according to claim 1, wherein the chlorinated polyvinyl chloride has a chlorine content of 63 to 72% by mass.
 3. The resin composition for molding according to claim 1, wherein the acrylic resin is a polymer of methyl (meth)acrylate.
 4. The resin composition for molding according to claim 1, wherein the impact resistance modifier is a methyl methacrylate-butadiene-styrene copolymer.
 5. The resin composition for molding according to claim 1, wherein the ratio of the impact resistance modifier to the acrylic processing aid (impact resistance modifier/acrylic processing aid) is 7.0 or less.
 6. The resin composition for molding according to claim 1, further comprising a thermal stabilizer.
 7. The resin composition for molding according to claim 1, which is free from β-diketone.
 8. The resin composition for molding according to claim 6, comprising the thermal stabilizer in an amount of 0.4 to 10 parts by mass relative to 100 parts by mass of the chlorinated polyvinyl chloride.
 9. A molded body molded from the resin composition for molding according to claim
 1. 10. The resin composition for molding according to claim 1, wherein the impact resistance modifier differs from the acrylic processing aid.
 11. The resin composition for molding according to claim 1, further comprising an antioxidant, wherein the antioxidant has a loss in quantity on heating at 200° C. of less than 5% by mass.
 12. The resin composition for molding according to claim 1, wherein the chlorinated polyvinyl chloride has a gelling time of 100 to 200 seconds.
 13. The resin composition for molding according to claim 1, further comprising two or more lubricants. 